A while back I wrote Asciimg, a minimalistic tool that can display images within a terminal. The tool implements a rudimentary dithering algorithm to translate colour intensities to ascii characters. I was recently playing around with it and thought of a few creative ways to put it to use.

If you wish to try the examples below yourself, the source code for Asciimg is available at github.

The experiments presented below are of limited practical value, and the way they are implemented is not particularly efficient. They are however a lot of fun to play with.

Image slideshows

In this example I wanted to create a simple slideshow of a set of images. Asciimg’s threshold switch is used to create a fade-in effect while transitioning to each new image. To facilitate faster image loading and avoid putting unnecessary strain on my SSD, I create a ramdisk, and copy the images into the respective mapped directory.

$ sudo mkdir /tmp/ramdisk
$ sudo chmod 777 /tmp/ramdisk
$ sudo mount -t tmpfs -o size=1024m myramdisk /tmp/ramdisk
$ cd /tmp/ramdisk    

The slideshow logic is straight forward and can be trivially implemented in any language. Here’s how to do it in a simple bash shell script one-liner:

$ for i in *.jpg; do for j in {25..1}; do sleep 0.02 && asciimg "$i" -threshold `echo "scale=3;$j/25" | bc` -res ${COLUMNS}x${LINES}; done; sleep 1; done    

This is what it looks like:

Videos

The next logical step is of course to try and play videos within the terminal. This example is slightly more elaborate. I use ffmpeg to read a video file and dump the frames read to an image file in the ramdisk I created above.

$ ffmpeg -re -i video.mp4 -y -update 1 -s 200x200 /tmp/ramdisk/frame.jpg    

In another terminal I then use the watch tool to run Asciimg and display that image in the terminal every 0.1 seconds.

$ watch -n0.1 asciimg frame.jpg -res ${COLUMNS}x${LINES}    

To demonstrate this, I recorded a clip from Carl Sagan’s 1980 Cosmos series, episode 1: The shores of the cosmic ocean. This is what it looks like: